As used herein, the term "biopsy" refers to the collection of a soft tissue specimen for purposes of examination, disease identification and diagnosis. Typically, biopsy procedures are performed to obtain specimens of tissue from an internal organ of suspect for detection of disease conditions, such as cancer, and are of particular utility in determining the extent of the spread of the disease prior to the performance of surgery or therapy. Where, for instance, an abnormality is suspected in a deeply located soft tissue organ such as the liver, spleen, pancreas, glands, etc., or where a growth has been located and it is desired to determine the nature and extent of the growth, a biopsy may be performed in order to obtain tissue specimens for laboratory examination. In general, biopsy procedures are preferred over the difficulty and trauma of exploratory surgery.
Referring now to FIG. 1A, a two piece biopsy needle 10 is commonly employed for obtaining tissue core specimens and comprises a small diameter, long tubular cannula 12 and a long, thin, sharp-tipped stylet 14 located inside the cannula 12 and movable relative to the cannula. The stylet 14 is provided with a specimen notch 16 on its periphery near a proximal tip of the stylet. The promixal end of the cannula 12 may be sharpened.
The biopsy needle 10 is inserted through a small incision or puncture made in the skin and driven into the body until its sharpened end enters the organ 18 of suspect. During this insertion stage of the procedure, the stylet 14 is positioned within the cannula 12 so that no more than the sharp tip of the stylet 14 is exposed; the specimen notch 16 is covered by the cannula 12.
Referring now to FIG. 1B, once the instrument 10 has been positioned at the site for the biopsy, the stylet 14 is driven into the organ 18 far enough to expose the specimen notch 16 of stylet 14. Soft body tissues of the organ 18 will then prolapse into the specimen notch 16.
Referring now to FIG. 1C, the cannula 12 is then advanced along the stylet 14 in order to cover the specimen notch 16. This forward movement of the cannula 12 cuts out a specimen 20 of the prolapsed tissue, which specimen 20 becomes retained in the specimen notch 16 of the stylet 14. With the cannula 12 still concealing the specimen 20 in the specimen notch 16, the biopsy needle assembly 10 may then be withdrawn carefully from the target site. Thereafter, the cannula 12 is once again retracted in order to expose the specimen notch 16 of the stylet 14, creating access to the tissue specimen 20 contained therein.
In all biopsies, it is desirable to perform the cutting procedure quickly in order to prevent the prolapsed tissue in the specimen notch 16 from being displaced outwardly during advance of the cannula 12 along the stylet 14. Slow movement by the cannula 12 might result in an insufficient specimen 20 being obtained. Numerous prior art devices have been developed in order to automate the sequential advance of the stylet 14 and the cannula 12. In order the achieve the requisite precise and coordinated mechanical motions, the prior art devices utilize relatively complex mechanical systems requiring a large number of parts and complex assemblies. Because of this, such prior art devices tend to be relatively expensive, cumbersome and unreliable. There is therefore a need in the prior art for a biopsy needle device which incorporates a simplified design requiring fewer parts and therefore less complicated, more compact assembly. The present invention is directed toward meeting those needs.